Snake Oil Science:
The Truth About Complementary and Alternative Medicine

R. Barker Bausell

The question Bausell asks in Snake Oil Science is not whether
complementary and alternative medicine (CAM) works — it clearly does —
but whether any CAM treatments work better than placebos. The short
answer is "no", but getting to that involves explanations of CAM,
placebos, double-blind randomised trials, and the problems of making
causal inferences about therapies.

Bausell begins with a typology of CAM, classifying it into five kinds:
indigenous medical systems such as traditional Chinese or Ayurvedic;
nonindigenous medical systems such as osteopathy, naturopathy, homeopathy,
and chiropractic; spiritual/energy healing; relaxation-oriented therapies;
and extensions of conventional science such as chelation, biofeedback and
"natural" drugs.

Placebos moved properly into the realm of science with Henry Beecher's
famous 1955 paper "The Powerful Placebo". Bausell considers a number
of different definitions, with his favourites including: "any genuine
psychological or physiological response to an inert or irrelevant
substance or procedure" and "any medical treatment that can have a
therapeutic effect only if administered to a patient who is aware that
he or she is receiving a medical treatment".

Three chapters are devoted to the problems of making valid causal
inferences, looking in turn at the "natural impediments" that affect
patients, practitioners and therapists, and scientists. Patients
can easily be misled by the natural history of their ailments, with
naturally fluctuating levels of pain mistaken for treatment effects.
Practitioners are misled by biases in the selection and attrition of
patients seeking help. And scientists can be misled by patient natural
history, unconscious experimenter bias, outcome selection, regression to
the mean, and patient behaviour changing under observation (the Hawthorne
effect), among other factors.

The best science involves randomized placebo control groups, but these
are not always easy to implement: placebo treatments for manipulation
therapies (or drugs with side effects) are difficult to implement
and, compounded by the need to obtain informed consent, can result in
incomplete blinding and differential attrition. So Bausell considers
some general rules for judging the credibility and plausibility of
scientific evidence.

After this background, and a brief account of his own experience
researching acupuncture, Bausell begins his argument proper. He begins
by "proving the obvious", with tests of the placebo effect and of the
role of conditioning. From these he concludes:

"The placebo effect is real and is capable of exerting at least a
temporary pain reduction effect. It occurs only in the presence
of the belief than an intervention (or therapy) is capable
of exerting this effect. This belief can be instilled through
classical conditioning, or simply by the suggestion of a respected
individual that this intervention (or therapy) can reduce pain."

It is probably only responsible for part of placebo effects, but
experiments reveal a likely biochemical explanation for placebo pain
reduction, involving the release of natural opioids.

"The placebo effect has a plausible, biochemical mechanism of
action (at least for pain reduction), and that mechanism of
action is the body's endogenous opioid system."

Returning to CAM, Bausell analyses high quality trials — that is,
randomised trials with a credible placebo control group, at least fifty
participants, and an attrition rate under 25%, published in high-quality
peer-reviewed journals. Out of twenty one such trials, there was only
one positive result, which is about what you'd expect by chance, testing
at a 0.05 level of significance.

An alternative approach is that taken by the Cochrane Collaboration, to
systematically review all the trials of a therapy and to analyze them
together. In addition to general trial quality concerns, the biggest
problem with such reviews is publication bias: positive results are
vastly more likely to get published than negative ones. Surveying nearly
one hundred of the best quality reviews of CAM therapies reveals some
notionally positive results, but these are always qualified by extremely
weak support or poor quality evidence. Bausell concludes:

"There is no compelling, credible scientific evidence to suggest
that any CAM therapy benefits any medical condition or reduces
any medical symptom (pain or otherwise) better than a placebo."

A chapter then considers the putative mechanisms of CAM treatments,
which range from the manifestly ridiculous such as homeopathy to the
perfectly plausible but unverified such as chiropractic.

"No CAM therapy has a scientifically plausible biochemical
mechanism of action over and above those proposed for the
placebo effect."

A final chapter considers some of the broader factors behind pathological
science, looking at the role of the media and education. Bausell finishes
with some tips on how to make best use of the placebo effect in selecting
a CAM treatment and therapist.

On the surface Snake Oil Science is, as the title and subtitle suggest,
a debunking of CAM, but it is more fundamentally about the nature of
scientific inference and methodological issues in the evaluation of
medical therapies. It doesn't address drug development or government
regulatory regimes at all, but much of it applies just as well to
evaluation of clinical studies by big pharmaceutical companies — some
of the social issues are different, but the underlying epistemological
issues are the same.

Snake Oil Science is unlikely to educate, or even be read by, CAM
adherents or practitioners from the more anti-scientific end of the
spectrum, but will be useful for those with more empirical approaches.
It could also be read by those without any particular interest in CAM,
seeking an explanation of why blinded randomised placebo trials are
important and how they work.